They are characterized by their insolubility or very slight solubility in water; as examples may be mentioned erythrinic acid in Roccella and Lecanora; evernic acid in species of Evernia, Ramalina and Cladonia; lecanoric acid in Lecanora, Gyrophora.

Amongst other lichens affording red, purple or brown dyes may be mentioned Ramalina scopulorum, Parmelia, saxatilis and P. omphalodes, Umbilicaria pustulate and several species of Gyrophora, Urceolaria scruposa, all of which are more or less employed as domestic dyes.

At one time also some species were used in the arts for supplying a gum as a substitute for gum-arabic. These were chiefly Ramalina fraxinea, Evernia prunastri and Parmelia physodes, all of which contain a considerable proportion of gummy matter (of a much inferior quality, however, to gum-arabic), and were employed in the process of calico-printing and in the making of parchment and cardboard.

Species of Usnea and Ramalina, also Evernia furfuracea and Cladonia rangiferina, were used in the art of perfumery.

The chief of those employed for one or other, and in some cases for several, of these purposes were Cladonia pyxidata, Usnea barbata, Ramalina farinacea, Evernia prunastri, Cetraria islandica, Sticta pulmonaria, Parmelia saxatilis, Xanthoria parietina and Pertusaria amara.